Smart card holders of this type are used when the intention is to hold a smart card in a device for a reading or writing operation and the smart card must not be removed from the device during the writing or reading operation on account of the nature of the data it contains.
Such cases arise, for example, when financial transactions are performed, for example when the smart card is used as a cash card, or in the case of digital tachographs in which smart cards are used to identify the driver and/or to store driver- and vehicle-specific data. Since tachographs are generally used for statutory reasons, particularly stringent requirements are imposed in terms of security against manipulation, in order to ensure the evidentiary value of the recorded data. At the start of a journey, the smart card is inserted into the digital tachograph and locked in the inserted position. The smart card must be ejected automatically by the device only when said device is appropriately actuated.
The abovementioned smart card holders preferably operate in a semiautomatic manner, that is to say the smart card is pushed in manually and the locking arrangement is activated by means of this insertion operation. In contrast, the card is unlocked and ejected automatically under the control of the device.
The provision of a suitable locking mechanism is an essential measure for providing the security against manipulation. To date, this locking has been performed by means of a track guide which operates two locking slides. This mechanism is accommodated in a very low overall height. Two hardened pins which run in grooves are riveted to the slides as guide elements for the transverse movement. A further hardened pin is riveted to the opposite side and the device is actuated for the transverse movement via the tracks using this further hardened pin. A range of problems are encountered with this design from the prior art. On account of two pins being guided in grooves, a large tilting angle is produced even with low tolerances, for example an angular play of 8° results with an axial distance of 10 mm and a 0.1 mm gap. During operation, the problems arise of the riveted pins sometimes absorbing relatively high forces and the depth to which the cylinder is pressed in being very low, in particular since another depression for recessing the riveting arrangement has to be made in this case. Therefore, the pins may come loose during relatively long-term operation.
Production has been made more costly by the fact that the hardened pins are not all arranged on one side. Due to this, the part has to be machined twice, as a result of which manufacturing costs are increased. The riveted arrangements have to be recessed since a very low overall height is desired for the mechanism and the parts move relative to one another and must not get caught on one another in the process. This also leads to an increase in costs.